The use of electromagnetic and sound waves to communicate information is well known in the prior art. The apparatus and method may involve amplitude modulation, frequency modulation, polarization modification or wave train interruption for a single wave train.
For a slit or aperture not too much larger than the wavelength of the wave train, diffraction will occur as the wave passes through the slit. The wave spreads laterally outside the geometric collimation limits. The intensity of the wave passes through maxima and nulls as the angle from beam axis direction increases, the magnitude of the maxima rapidly decreasing as the angle increases.
While diffraction is always present in the propagation of a single wave train, it is not involved in the basic communication mechanism of amplitude modulation, frequency modulation, polarization modification or wave train interruption. Radiation of one frequency is used for amplitude modulation, polarization modification and wave train interruption while a bandwidth of frequencies is associated with frequency modulation.
Coherence within one beam of light is utilized in U.S. Pat. No. 3,776,616, issued to N. Douklias on Dec. 4, 1973, wherein a multichannel correlator illuminates an object for the purpose of producing a hologram.
The prior art discloses devices in which a single wave train may be refracted or diffracted with respect to itself. However, the need remains for a binary logic apparatus and method for two coherent input beams to perform logic operations "AND", "OR" or "NOT". These binary logic operations of "AND", "OR", and "NOT" are the logic blocks used to construct the most sophisticated and complex digital circuits.